Measuring molecular self-interaction can help to indicate whether particular particles will aggregate or crystallize. One measure of self-interaction is the B22 interaction parameter. Prior art methods of detecting the B22 interaction parameter are described in U.S. Pat. No. 7,630,076 and US Appl. No. 20070291265, which are herein incorporated by reference. As shown in FIG. 1, these methods involve performing scattering and ultraviolet (UV) absorbance measurements on a sample in a flow cell.